gpio: lpc32xx: fix issues with port3 gpio

gpio: lpc32xx: fix issues with port3 gpio

The current simplify lpc32xx gpio driver implementation assume a
maximum of 32 GPIO per port; there are a total of 22 GPI, 24 GPO
and 6 GPIO to managed on port 3.

Update the driver to fix the following:
1) When requesting GPI_xx and GPO_xx on port 3 (xx is the same number)
   the second call to "gpio_request" will return -EBUSY.

2) The status of GPO_xx pin report the status of the
   corresponding GPI_xx pin when using the "gpio status" command.

3) The gpio driver may setup the direction register for the wrong
   gpio when calling "gpio_direction_input" (GPI_xx) or
   "gpio_direction_output" (GPO_xx) on port 3; the call to the
   direction is require to use the "gpio status" command.

The following change were done in the driver:
1) port3 GPI are cache in a separate 32 bits in the array.
2) port3 direction register written only for GPIO pins.
3) port3 GPO & GPIO (as output) are read using "p3_outp_state".
4) LPC32XX_GPI_P3_GRP updated to match the change.

Signed-off-by: Sylvain Lemieux <slemieux@tycoint.com>